None.
Not Applicable.
1. Field of the Invention
This invention relates generally to devices that support the weight of a person in a seated position and particularly to devices that are capable of changing shape according to the occupant, and more particularly, this invention relates to devices that support and change shape according to the lumbar region of the occupant.
2. Related Art
Lumbar support devices have been integrated into seats to change their shape in the lumbar region, thereby allowing each occupant to adjust the support provided by the seat. The curvature and axial location of these devices are traditionally adjustable. When the back of the occupant engages the back of the seat, the curvature of the device presses the seat towards the occupant""s spinal column, and the axial location of the device can be positioned according to the size of the occupant, thereby accounting for differences in the occupant""s lumbar region with respect to the seat. It is generally known to provide manual actuation means and to alternatively provide powered actuation means for changing the curvature of the lumbar device and for changing the axial location of the lumbar device.
Typically, the curvature portion of these devices is constructed of a rigid material that is stamped into a particular shape or manufactured from individual components attached by hardware, such as rivets, screws, welds and bolts. Curvature changes are accomplished by bowing the curvature portion, usually pulling support structures toward each other. It is well known to pull on the supports with cables and some devices interpose structures between the supports to provide a mechanical advantage to the pulling action. In particular, U.S. Pat. No. 5,397,164 discloses a rod and a lever with springs and traction elements between supports and further discloses a cable running around a groove formed in a support plate in substitution for the lever. By substituting the cable running around the groove for the lever mechanism, the springs and traction elements are eliminated; however, the rod is required for both the lever mechanism and the grooved support plate. Additionally, the designs of these known devices require manual assembly operations, including the manual attachment of extension springs and assemblies requiring rivets or welds, and do not allow for a simplified assembly process.
Lumbar support devices using a resilient grid, such as those disclosed in U.S. Pat. Nos. 5,911,477 and 5,651,584 and incorporated by reference herein, provide good support qualities without excessive parts and are well suited for simplified assembly operations. These lumbar supports could be further improved with novel structures that provide a mechanical advantage and are also well suited for an automated manufacturing process.
It is in view of the above problems that the present invention was developed. The invention is a lumbar support device that can bow a flexible grid attached to a first bracket and a second bracket that slide on a track. Pulling on a cable segment that link the pair of brackets results in the bowing of the flexible grid. The cable segment is wrapped around the second bracket and is attached at its terminal end to the first bracket and its proximal end is engaged by a curvature cable actuator; wrapping the cable segment provides a mechanical advantage to the bowing resistance of the flexible grid. According to the present invention, the greatest mechanical advantage can be achieved by wrapping the cable segment around a pulley attached to the second bracket, and since no rod is necessary according to the present invention, this mechanical advantage can be achieved with fewer parts than the related art. The lumbar support device can also change the axial position of the flexible grid. A spring tension cable links an integrated bracket with the second bracket, and a compression spring is used to provide resistance to the cable and movement in an opposite direction.
In another embodiment, a lumbar support device includes a flexible grid that is bowed without any change in axial position. In yet another embodiment, a lumbar support device includes a grid that is moved axially without any change in curvature.
The track can be constructed from a base wire, known to be well suited to automatic manufacturing operations according to the patents incorporated by reference above and generally simplifying the assembly process. According to the patents incorporated by reference, it is known to slidably attach a bracket onto the base wire through apertures in the bracket and hold the bracket onto the base wire with bends in the base wire, to secure a bracket to the base wire between a dimple and a bend in the base wire, and to rotatably attach the flexible grid to a pair of brackets with a pair of pivot legs formed on each end of the border elements. Each of these attachments is accomplished using corresponding formations in the structures themselves, thereby eliminating any need for a weld, a rivet, or any other hardware. According to the simplified assembly process of the present invention, the integrated bracket slides onto the track and is secured to the track by a dimple at a fixed position in the track, the compression spring slides onto the track and is held in place between the integrated bracket and a slidably attached bracket, and the integrated bracket is linked with the second bracket using a press-fit connection at the end of the spring tension cable. For a powered lumbar support, the simplified assembly process also includes snap-fit connections between the integrated bracket and respective actuators.
Therefore, it is an object of this invention to provide a lumbar support unit capable of curvature movement having a mechanical advantage that uses fewer parts and hardware than the related art.
It is another object of the present invention to provide a lumbar support unit capable of axial movement that may be assembled with a minimum number of parts and hardware.
It is yet another object of the present invention to provide a lumbar support unit that is well suited to automatic assembly operations.
It is also an object of the present invention to provide a simplified assembly process for a lumbar support unit.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings in which like reference numbers indicate like elements.